Air eliminating device



Aug. 12, 1958 F. H. AINSWORTH AIR ELIMINATING DEVICE Filed Aug. 17, 1956 United States Patent Am ELIMINATING DEVICE Freedom H. Ainsworth, Salisbury, Mon, assignor to Syruington Wayne Corporation, Salisbury, Md, a corporation of Maryland Application August 17, 1956, Serial No. 694,78o

6 Claims. (Cl. 222-644) This invention relates to a device for eliminating gases and vapors such as air from a pipe line connecting a pump to a remote dispensing unit, and more particularly to a device for eliminating air from a system connecting a gasoline pump with a remote dispensing unit.

In systems for pumping gasoline currently used at service stations, means must be provided for eliminating air to insure that the meter measures a quantity of gasoline rather than a mixture of gasoline and air. A conventional dispensing unit which includes a pump of the suction lift type must include an air separating means between the pump and the meter in order to insure that purchasers are charged for the true quantity of gasoline delivered. In remote systems where a submerged pump supplies gasoline todispensing units through rather long pipe lines, a check valve is normally installed in the pipe line adjacent the pump. Purging means is provided between the discharge of the pump and the check valve to insure that no gases or vapors such as air are pumped into the supply lines. This is an extremely economical arrangement because only one air separating or purging means need be provided for one pump, which may su ply several remote dispensing units.

Each dispensing unit includes a manually opened control valve in its outlet nozzle which is held closed by pressure and which cooperates with the check valve adjacent the pump to maintain gasoline trapped in the lines at a positive pressure whenever the operator releases the control valve and allows it to shut 011. The pump usually is pressure controlled to shut off at a predetermined maximum pressure when the dispensing valves are allowed to close. It might accordingly appear that no air could enter the lines against this positive pressure. However, there is no positive assurance that leaks in these rather long pipe lines will not allow air to enter the system.

An object of this invention is to provide a simple economical means for eliminating air which may leak into fluid supply lines connecting a pump with a remote dispensing unit.

In accordance with this invention, a simple economical means is provided for eliminating air from a fluid piping system connecting a pump to a remote dispensing unit. The pump is connected to the system through a check valve. Purging means is provided between the pump and this check valve to insure that no air is pumped into the system. The discharge pipes connecting this check valve to the dispensing units are sloped downward to collect, at the outlet side of this check valve, any air which may leak into these lines. Conduit A relief valve is installed in this conduit and is set at a predetermined pressure below the shut otf pressure of the pump to allow a quantity of fluid, including the air trapped at the outlet side of the check valve, to flow back into the pump side of the check valve when the pump is stopped. The air is then removed by the aforemen- 2347,1453 Patented Aug, 12, 1958 ice this invention;

Fig. 2 is a schematic diagram of a portion of the embodiment shown in Fig. 1 which illustrates flow conditions when the pump is operating; and

Fig. 3 is a schematic diagram of the same portion of the embodiment shown in Fig. 2 illustrating conditions of flow when the pump is shut down.

In Fig. 1, a system 10 is shown which includes a submerged pump 12 installed near the bottom of a tank 14, for example an underground gasoline tank, which supplies several remote gasoline dispensing units 16 through an air eliminating unit 18, downwardly sloped supply piping 2b and vertical risers 21. The pump 12 is connected to this air eliminating unit 18 by a discharge line 22 and air purged by the air eliminating device 18 from the gasoline to be pumped into the supply line 20 is vented to the tank 14 by means of a return line 24 including a check valve'26.

Each dispensing unit 16 includes a flow meter and associated valve and other fittings which are schematically represented by rectangle 28. The dispensing nozzles of units 16 are designated by reference character 30, and a manually opened control valve 32 is installed at each of these nozzles. This control valve 32 is arranged to be held closed by line pressure, and supply line 20 is therefore effectively isolated between a check valve 34 (later described in detail) in air eliminating device 18 and control valves 32.

Figs. 2 and 3 show the details of air eliminating device 18, and respectively illustrate flow conditions when the pump is operating and when shut down. Figs. 2 and 3 are partially schematic or diagrammatic and indicate operative details only when necessary to impart an understandable description of the structure and operation of this invention. Details of construction have been eliminated wherever possible to simplify the description of this invention to facilitate an explanation of its basic features. Materials of the type suitable for a gasoline distribution system are used throughout such as aluminum, brass, iron or steel with precautions being taken that no sparking metals are used together.

Fig. 2 shows the air eliminating device 18 as it appears when the pump 12 is supplying gasoline to supply line 20. Air eliminating device 18 includes a'casing 36 which is divided into a supply or inlet chamber 33 and a discharge, outlet or collecting chamber 40 by a separating wall 42 including a vertical portion 44 and a horizontal portion 46. A port 48 is provided in the horizontal portion 46, for example, for allowing gasoline to flow from supply chamber 38 to discharge chamber 40. Check valve 34 controls this flow in a manner later described in detail.

A portion 50 of supply chamber 33 is separated from 4 discharge chamber 40 by means of vertical separating wall 44. Supply chamber portion 51) is accordingly positioned above port 48. Any air which may be present in supply chamber 38, therefore, rises to its highest portion 50 and is purged by a flow of gasoline through the return line 24 and check valve 26 back into tank 14.

Supply line piping 2% connecting discharge chamber 40 with dispensing units 16 is sloped downward to its junctions with risers 21 to allow any air which may leak into supply line 20 to rise or drift upward within supply line 20 towards air eliminating unit 18. Bubbles 52 represent air rising within supply line 20 which collect in the upper portion of discharge or collecting chamber 40 above check valve 34. A pocket of air within collecting chamber 40 is designated by reference character 54.

Check valve 34 includes, for example, a plunger 56 which is guided in its upward and downward travel by insertion of its upper stem 53- within tubular passage 60 provided in the upper portion 62 of chamber wall or casing 36. A portion of the chamber wall extends at 64 towards port 48 to provide a boss 64 for guiding the vertical movement of stem 58. Stem 53 is vertically fluted, splined or reduced in diameter, shown at 66, to decrease its frictional resistance on guide wall 69 and to permit a free fl of air from chamber 40 to chamber 63. A conduit or passageway 7b connects the upper portion of chamber 4A) to chamber 68 to permit air accumulating in chamber 4% to pass into chamber 68.

Check valve plunger 56 also includes, for example, a sealing disc 72 of conventional construction secured to the plunger by means of washer 74, lock washer 76, and fastening nut 75. A compression spring 80 is disposed between a shoulder 82 on boss 64 and washer 74 to help positively close check valve 34 when the pump is stopped.

A conduit or passageway 84 is provided, for example, extending completely through the center of plunger 56 for allowing air to dribble back into the supply chamber 38 when the pump is stopped. A relief valve 86 is installed, for example, in passageway 84 and is set and arranged to permit fluid to flow in the direction from the outlet side of the check valve to the inlet side only when the pressure at the outlet side is more than a predetermined pressure greater than the pressure at the inlet side and to prevent at all times a flow from the inlet side to the outlet side through passageway 84. Reset valve 86 is, for example, set at a predetermined pressure slightly below pump shut 01f pressure to allow a small quantity of fluid including air to flow back into the supply chamber 38 from the discharge chamber 40 when the pump is stopped. Relief valve 86 may also be installed at any point connecting discharge chamber 40 with supply chamber 38. It may be installed, for example, in vertical portion 44 of separating wall 42, but it is always installed in a manner which permits a flow through it only in a direction opposite to the flow through check valve 34.

Fig. -2 shows the check valve 34 in the open position with plunger 56 moved up and away from its seat 38 of port 48 by the flow of gasoline under pressure provided by pump 12 through discharge line 22 into chamber 38. Chamber 38 is accordingly full of gasoline provided under pressure from the pump. A quantity of the gasoline flowing back into the tank 14 through return line 24 removes any air trapped in the upper portion 50 of supply chamber 38. Any air which has dribbled back into supply chamber 38 through relief valve 86 is thereby circulated back into the tank 14 along with any other air that may be entrained in the pumped gasoline. When check valve 34 is in this opened condition, there is no differential pressure imposed across it, and relief valve 86, thereof, remains closed while pump 12 is operating and check valve 34 is open.

Supply chamber 40 is also filled with gasoline to a level above the inlet to supply line so that a supply of gasoline free of entrained air is supplied to a remote dispensing unit 16. Any air bubbles 52 which may leak into supply line 20 drift or rise towards the air eliminating unit 18 and accumulate in a pocket 54 at the top of discharge chamber 40. The condition shown in Fig. 2 is maintained as long as the pump continues pumping at its normal discharge pressure which may be, for example,

7 p. s. i.

As shown in Fig. 2, a quantity of air and vapors are trapped at the upper portion 54 of the discharge chamber 4d. These gases and vapors, including air, pass to the chamber 68 above valve stem 58 through passageway 70 and the clearance provided by the valve stem 58 and the guiding wall 60 of chamber 68.

Fig. 3 shows the condition of the air eliminating unit 13 and associated equipment when control valve 32 is allowed to close and when pump 12 is subsequently shut down. A small quantity of fluid including air is shown flowing back into supply chamber 38 which may be described or the pump side of the check valve 34. This back flow is caused by the following sequence of events.

Check valve 34 is slammed shut against seat 88 of port 48 by the pressure of the gasoline in line 20 aided by compression spring 80. When the pump shuts down, a pressure is maintained in line 20 substantially equal to the pump shut off pressure. The isolation of line 20 is cooperatively produced by the closure of dispensing nozzle control valves 32 aided by line pressure when the valves 32 are allowed to close.

Relief valve 86 is set to allow the passage of fluid from discharge chamber 40 back to supply chamber 38 until the pressure in line 20 is somewhere below pump shut off pressure. When pump shut ofi pressure is 28 p. s. i., for example, relief valve 86 may be set to maintain a pressure of 25 to 2 p. s. i., for example, in supply line 20 and discharge chamber 40 relative to inlet chamber 38 after control valves 32 are allowed to close and the pump is stopped. This causes a bleeding back of fluid from the supply line or outlet side of check valve 34 to the pump side of check valve 34 each time the pump is stopped. This flow of fluid forces ahead of it through relief valve 86, the air pocket 54 trapped in the discharge chamber or outlet side of the check valve. The entrapped air, therefore, leaks back into the pump side of the check valve where it is purged through the return line 24 when the pump is once again started.

The back flow of air and any other gases and vapors may be aided by thermal expansion, which occurs when the fluid in the supply line 20 attains a higher temperature than the gasoline in tank 14. This expansion is caused during most periods of the year because the supply line 20 is closer to the surface of the ground than tank 14 which exposes it to more direct rays of sunlight. In colder periods of the year, however, the system is still operative because the relief valve 86 is set at a predetermined pressure lower than pump shut off pressure to allow a bleeding back of fluid from the isolated supply line 20 into the discharge chamber 38 each time the pump is shut down. A pressure accumulator may be incorporated in line 20 to promote this back flow.

The embodiment of this invention shown in this application relates to a gasoline distributing system, but it is apparent to one skilled in the art that it may be applied to any fluid distribution system in which air or other gases or vapors may leak into or be generated for any reason within the distribution system.

What is claimed is:

1. A device for eliminating gases and vapors from a fluid piping system which connects a pump to a remote dispensing unit including a check valve which has purging means connected to its inlet side and its outlet side connected by a downwardly sloping supply line to said remote dispensing unit, said device comprising wall means providing a collecting chamber disposed adjacent and connected to said outlet side of said check valve for accumulating gases and vapors in said system adjacent said check valve, conduit means connecting said inlet and outlet sides of said check valve, a relief valve disposed within said conduit means, said relief valve being constructed and arranged to permit said fluid to flow in the direction from said outlet side of said check valve to said inlet side of said check valve only when the pressure at said outlet side is more than a predetermined pressure greater than the pressure at said inlet side, and said predetermined pressure being less than the pressure within said system at the outlet side of the check valve when said check valve and said system are closed to permit a quantity of fluid including any gases and vapors trapped at the outlet side of said check valve to flow back into said inlet side of said check valve after said check valve closes.

2. A device as set forth in claim 1 wherein a control valve is provided at said dispensing unit for isolating said supply line under pressure.

3. A device as set forth in claim 1 wherein wall means are constructed and arranged to provide an inlet chamber disposed at the inlet side of said check valve, said inlet chamber includes a portion thereof extending above said check valve to collect gases and vapors at a point in said inlet chamber remote from said check valve, and channel means is provided in an upper portion of said inlet chamber to permit some of the fluid supplied to the inlet side of said check valve to be removed through said channel means to purge gases and vapors trapped Within said upper portion of said inlet chamber.

4. A device as set forth in claim 1 further including wall means constructed and arranged to provide separate inlet and outlet chambers respectively disposed at the inlet and outlet sides of said check valve, said check valve being mounted in a dividing Wall separating said chambers, and said dividing Wall extending above said check valve to permit gases and vapors discharged through said relief valve to collect in an upper portion of said inlet chamber remote from said check valve, and said purging means being connected to said upper portion of said inlet chamber.

5. A device as set forth in claim 1 wherein said check valve includes a stem and said collecting chamber includes a protruding wall having a guide chamber for said stem, said guide chamber being disposed above said collecting chamber to provide said guide chamber to receive gases and vapors accumulated in said discharge chamber, and flow passage means extending through said protruding wall to connect said collecting chamber with said guide chamber to conduct said gases and vapors into said guide chamber.

6. A device as set forth in claim 5 wherein said stem is tubular with its hollow interior passageway disposed in line with the passageway through said check valve, and said relief valve is mounted within said passageway in said check valve.

References Cited in the file of this patent UNITED STATES PATENTS 

